The present invention relates to apparatus for sensing the position or size of a remote object regardless of its distance away from the apparatus.
There are many applications for devices to detect the position of an object with respect to some fixed axis or to detect the size of an object from a remote location. For example, in robotics, it is desirable for the robot to be able to determine where a particular object it is seeking lies so that it can move toward the object for purposes of contact therewith. Also, in assembly line applications, it is often necessary to gauge the size of an object, such as a label on a container, from a remote location.
In the past, attempts to use optical systems to determine the position or size of a remote object have been hindered when the distance to the object is not known or when the distance may vary. The difficulty arises because the size of the object's image, as seen through the optical system, changes with changes in the distance to the object. Accordingly, the radiation sensor, which is employed to receive the image and to provide information concerning features of the object, produces different outputs with changes in the distance to the object. Thus, the output of the detector will be in error unless the objects can be controlled to always be at a predetermined fixed range or the distance can be measured so that the output can be modified to compensate for range differences. While these solutions are possible, they are unduly complicated and costly.